Summary

• A vulnerability in the Zone-Based Firewall (ZBFW) component of Cisco IOS Software could allow an unauthenticated, remote attacker to cause an affected device to hang or reload.
  
  The vulnerability is due to improper processing of specific HTTP packets when the device is configured for either Cisco IOS Content Filtering or HTTP application layer gateway (ALG) inspection. An attacker could exploit this vulnerability by sending specific HTTP packets through an affected device. An exploit could allow the attacker to cause an affected device to hang or reload.
  
  Cisco has released software updates that address this vulnerability.
  
  Workarounds that mitigate this vulnerability are not available.
  
  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-cce
  

  Note: The September 25, 2013, Cisco IOS Software Security Advisory bundled publication includes eight Cisco Security Advisories. All advisories address vulnerabilities in Cisco IOS Software. Each Cisco IOS Software Security Advisory lists the Cisco IOS Software releases that correct the vulnerability or vulnerabilities detailed in the advisory as well as the Cisco IOS Software releases that correct all Cisco IOS Software vulnerabilities in the September 2013 bundled publication.

  Individual publication links are in "Cisco Event Response: Semiannual Cisco IOS Software Security Advisory Bundled Publication" at the following link:

  http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep13.html

Affected Products

• Vulnerable Products

  Cisco devices that are running affected Cisco IOS Software versions are vulnerable when HTTP ALG inspection or Cisco IOS Content Filtering is configured under the ZBFW.
  
  To verify whether the HTTP ALG inspection under the ZBFW is configured on a device use the show running-config command. If the service policy that is attached to any zone contains a policy map that contains the command service-policy http name then the device is configured for HTTP ALG. The following is the output from the show running-config command executed on a device running Cisco IOS Software that has the HTTP ALG inspection enabled under the ZBFW configuration:
  

  ios-fw#show running-config
  
  < output removed for brevity >
  
  policy-map type inspect in->out
   class type inspect filtered-hosts
    inspect
    service-policy http http_bad
   class class-default
    drop
  !
  zone security inside
  zone security outside
  zone-pair security in-to-out source inside destination outside
   service-policy type inspect in->out
  < output removed for brevity >
  ios-fw#
  
  
  

  To verify whether Cisco IOS Content Filtering under the ZBFW is configured on a device use the show policy-map type inspect zone-pair urlfilter | include URL Filtering privileged EXEC command and check for output.  A blank line indicates that the feature is not enabled.  Output with URL Filtering is in indicates the device is configured with Cisco IOS Content Filtering under ZBFW.  The following is the output from the show policy-map type inspect zone-pair urlfilter | include URL Filtering command executed on a device running Cisco IOS Software that has Cisco IOS Content Filtering enabled under the ZBFW configuration:
  

  ios-fw#show policy-map type inspect zone-pair urlfilter | include URL Filtering
          URL Filtering is in 
  ios-fw#

  Note: Cisco IOS Content Filtering using ip inspect and ip urlfilter commands are not affected.
  

  To determine the Cisco IOS Software release that is running on a Cisco product, administrators can log in to the device and issue the show version command to display the system banner. The system banner confirms that the device is running Cisco IOS Software by displaying text similar to "Cisco Internetwork Operating System Software" or "Cisco IOS Software." The image name displays in parentheses, followed by "Version" and the Cisco IOS Software release name. Other Cisco devices do not have the show version command or may provide different output.

  The following example identifies a Cisco product that is running Cisco IOS Software Release 15.0(1)M1 with an installed image name of C3900-UNIVERSALK9-M:

  Router> show version 
  Cisco IOS Software, C3900 Software (C3900-UNIVERSALK9-M), Version 15.0(1)M1, RELEASE SOFTWARE (fc1)
  Technical Support: http://www.cisco.com/techsupport
  Copyright (c) 1986-2009 by Cisco Systems, Inc.
  Compiled Wed 02-Dec-09 17:17 by prod_rel_team

  !--- output truncated 

  Additional information about Cisco IOS Software release naming conventions is available in "White Paper: Cisco IOS and NX-OS Software Reference Guide" at http://www.cisco.com/web/about/security/intelligence/ios-ref.html.

  Products Confirmed Not Vulnerable

  Cisco IOS XR Software is not affected by this vulnerability.
  
  Cisco IOS XE Software is not affected by this vulnerability.
  
  No other Cisco products are currently known to be affected by this vulnerability.

Details

• A vulnerability in the Zone-Based Firewall (ZFW) component of Cisco IOS Software could allow an unauthenticated, remote attacker to cause an affected device to hang or reload.
  
  The vulnerability is due to improper processing of specific HTTP packets when the device is configured for content filtering or HTTP application layer gateway inspection. An attacker could exploit this vulnerability by sending specific HTTP packets through an affected device. An exploit could allow the attacker to cause an affected device to hang or reload.
  Only transit traffic can trigger this vulnerability; HTTP traffic destined to a vulnerable device cannot trigger this vulnerability.
  
  In devices that meet the vulnerable configuration criteria, valid HTTP packets could trigger this vulnerability.   This vulnerability can only be exploited with IPv4 traffic.  IPv6 traffic cannot be used to exploit this vulnerability.
  
  This vulnerability has been documented in Cisco Bug ID CSCtx56174 (registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) ID CVE-2013-5476. 
  

Workarounds

• Workarounds that mitigate this vulnerability are not available.

Fixed Software

• When considering software upgrades, customers are advised to consult the Cisco Security Advisories, Responses, and Notices archive at http://www.cisco.com/go/psirt and review subsequent advisories to determine exposure and a complete upgrade solution.
  
  In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
  

  Cisco IOS Software

  Each row of the following Cisco IOS Software table corresponds to a Cisco IOS Software train. If a particular train is vulnerable, the earliest releases that contain the fix are listed in the First Fixed Release column. The First Fixed Release for All Advisories in the September 2013 Bundled Publication column lists the earliest possible releases that correct all the published vulnerabilities in the Cisco IOS Software Security Advisory bundled publication. Cisco recommends upgrading to the latest available release where possible.

  The Cisco IOS Software Checker allows customers to search for Cisco Security Advisories that address specific Cisco IOS Software releases. This tool is available on the Cisco Security (SIO) portal at https://sec.cloudapps.cisco.com/security/center/selectIOSVersion.x

  
  

  Major Release	Availability of Repaired Releases
  Affected 12.0-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  There are no affected 12.0 based releases
  Affected 12.2-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  There are no affected 12.2 based releases
  Affected 12.3-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  There are no affected 12.3 based releases
  Affected 12.4-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  There are no affected 12.4 based releases
  Affected 15.0-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  There are no affected 15.0 based releases
  Affected 15.1-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  15.1EY	Not vulnerable	Vulnerable; First fixed in Release 15.2S
  15.1GC	Vulnerable; First fixed in Release 15.1M Releases up to and including 15.1(2)GC2 are not vulnerable.	Vulnerable; First fixed in Release 15.1M
  15.1M	Releases including and prior to 15.1(4)M1 are not vulnerable. First fixed in 15.1(4)M6.	15.1(4)M7
  15.1MR	Not vulnerable	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
  15.1MRA	Not vulnerable	15.1(3)MRA2
  15.1S	Not vulnerable Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	15.1(3)S6 Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.1SG	Not vulnerable Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	15.1(2)SG1 Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.1SNG	Not vulnerable	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
  15.1SNH	Not vulnerable	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
  15.1SNI	Not vulnerable	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
  15.1SVD	Not vulnerable	Not vulnerable
  15.1SVE	Not vulnerable	Not vulnerable
  15.1SVF	Not vulnerable	Not vulnerable
  15.1SY	Not vulnerable	15.1(1)SY2; Available on 28-OCT-13 15.1(2)SY
  15.1T	Not vulnerable	Vulnerable; First fixed in Release 15.1M
  15.1XO	Not vulnerable	Not vulnerable
  Affected 15.2-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  15.2E	Not vulnerable	Not vulnerable
  15.2GC	15.2(4)GC	Vulnerable; migrate to any release in 15.4T
  15.2JA	Not vulnerable	15.2(4)JA1
  15.2JAX	Not vulnerable	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
  15.2JB	Not vulnerable	15.2(2)JB2
  15.2JN	Not vulnerable	Not vulnerable
  15.2M	Not vulnerable	15.2(4)M4
  15.2S	Not vulnerable Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	15.2(4)S4 Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.2SA	Not vulnerable	15.2(2)SA
  15.2SNG	Not vulnerable	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
  15.2SNH	Not vulnerable	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
  15.2SNI	Not vulnerable	Vulnerable; First fixed in Release 15.3S
  15.2T	15.2(1)T4 15.2(3)T4	15.2(3)T4
  Affected 15.3-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  There are no affected 15.3 based releases

  Cisco IOS XE Software

  Cisco IOS XE Software is not affected by the vulnerability disclosed in this advisory.

  Cisco IOS XR Software

  Cisco IOS XR Software is not affected by any of the vulnerabilities that are disclosed in the September 2013 Cisco IOS Software Security Advisory Bundled Publication.

Exploitation and Public Announcements

• The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
  
  This vulnerability was discovered when handling customer service requests.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-cce

Revision History

• Revision 1.0

  2013-September-25

  Initial public release

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